[#1445] services/tree: Cache the list of container nodes

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/services/tree/container.go

@@ -0,0 +1,90 @@
+package tree
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"sync"
+
+	"github.com/hashicorp/golang-lru/simplelru"
+	"github.com/nspcc-dev/neofs-node/pkg/core/container"
+	"github.com/nspcc-dev/neofs-node/pkg/services/object_manager/placement"
+	cidSDK "github.com/nspcc-dev/neofs-sdk-go/container/id"
+	netmapSDK "github.com/nspcc-dev/neofs-sdk-go/netmap"
+)
+
+type containerCache struct {
+	sync.Mutex
+	nm  *netmapSDK.NetMap
+	lru *simplelru.LRU
+}
+
+func (c *containerCache) init() {
+	c.lru, _ = simplelru.NewLRU(defaultContainerCacheSize, nil) // no error, size is positive
+}
+
+type containerCacheItem struct {
+	cnr   *container.Container
+	local int
+	nodes []netmapSDK.NodeInfo
+}
+
+const defaultContainerCacheSize = 10
+
+// getContainerNodes returns nodes in the container and a position of local key in the list.
+func (s *Service) getContainerNodes(cid cidSDK.ID) ([]netmapSDK.NodeInfo, int, error) {
+	nm, err := s.nmSource.GetNetMap(0)
+	if err != nil {
+		return nil, -1, fmt.Errorf("can't get netmap: %w", err)
+	}
+
+	cnr, err := s.cnrSource.Get(cid)
+	if err != nil {
+		return nil, -1, fmt.Errorf("can't get container: %w", err)
+	}
+
+	cidStr := cid.String()
+
+	s.containerCache.Lock()
+	if s.containerCache.nm != nm {
+		s.containerCache.lru.Purge()
+	} else if v, ok := s.containerCache.lru.Get(cidStr); ok {
+		item := v.(containerCacheItem)
+		if item.cnr == cnr {
+			s.containerCache.Unlock()
+			return item.nodes, item.local, nil
+		}
+	}
+	s.containerCache.Unlock()
+
+	policy := cnr.Value.PlacementPolicy()
+
+	rawCID := make([]byte, sha256.Size)
+	cid.Encode(rawCID)
+
+	cntNodes, err := nm.ContainerNodes(policy, rawCID)
+	if err != nil {
+		return nil, -1, err
+	}
+
+	nodes := placement.FlattenNodes(cntNodes)
+
+	localPos := -1
+	for i := range nodes {
+		if bytes.Equal(nodes[i].PublicKey(), s.rawPub) {
+			localPos = i
+			break
+		}
+	}
+
+	s.containerCache.Lock()
+	s.containerCache.nm = nm
+	s.containerCache.lru.Add(cidStr, containerCacheItem{
+		cnr:   cnr,
+		local: localPos,
+		nodes: nodes,
+	})
+	s.containerCache.Unlock()
+
+	return nodes, localPos, err
+}